A. Takagi

(Pb, La)(Zr, Ti)O3 Films by Multiple Electrophoretic Deposition/Sintering Processing

(Pb, La)(Zr, Ti)O3 films were prepared by multiple (electro-phoretic deposition/sintering) cycles, using fine crystalline powders, acetone, nitrocellulose and HNO3 as suspensions. Dense, strong films having a final thickness of 15~25 µm were formed reproducibly on platinum substrates. Due to tight contact between the film and rigid substrate, during firing, lattice constants of sintered films were 0.3~0.5% longer than those of bulk with the same composition. Reflecting these lattice expansions, the Curie temperature of sintered films shifted to higher temperature as compared to that of bulks with the same composition. All films with the composition 8/65/35 and 9/65/35 are ferroelectric and thus exhibit pyroelectric, and piezoelectric activities. These characteristics of the films are modified from those of the bulk form by crystal lattice distortion.

Further evaluation of the high intensity plasma sputter heavy negative ion source

In this report, we provide more detailed information on the high intensity heavy negative ion source described previously. Intensity vs time spectra, mass distribution data and source operational data are presented for Au, Cu, Ni and CuO sputter probes. Sputter probe voltage limited beam intensities of 10.2, 8.2, 5.1 and 4.5 mA, respectively have been realized from these sputter probes. The results of emittance measurements for Au and Ni probes indicate a rather strong dependence on beam intensity, as expected from space charge considerations. The source, when operated in pulsed mode, holds considerable promise for use in conjunction with tandem electrostatic accelerator/synchrotron injection applications. The high intensity capabilities of the source make it a viable candidate for generating mA intensity level, cw ion beams for a variety of other applications, including ion implantation.

A versatile high intensity plasma sputter heavy negative ion source

Abstract A multicusp magnetic field plasma surface ion source, normally used for H − ion beam formation, has been utilized for the generation of high intensity, pulsed, heavy negative ion beams suitable for a variety of uses including tandem electrostatic accelerator/synchrotron injection applications. Sputter probe voltage limited total ion currents of 5.5, 8.2, 5.1 and 4.5 mA (peak intensity) have been produced from Au, Cu, Ni and CuO sputter probes, respectively. The mass distributions of these ion beams are found to be dominated by Au − , Cu − , Ni − and O − atomic species, respectively. The source offers the interesting prospect of providing cw negative ion beams at mA intensity levels of the commonly used semiconducting material dopants (e.g. B − , P − , As − and Sb − ) as well as O − for isolation barrier formation. Illustrative examples of intensity versus time and the mass distribution of ion beams extracted from a Ni sputter probe, along with brief descriptions of the source, experimental apparatus and procedures followed during the course of these investigations, are presented in this report.

High field-gradient cavities loaded with magnetic alloys for synchrotrons

Very high field-gradient has become available by a new magnetic alloy (MA)-loaded cavity developed for high intensity proton synchrotrons. The available RF voltage per core is ten times larger than that of the ordinary ferrite core. The maximum voltage of 20 kV has been achieved by the high-field gradient cavity (HGC) of 40 cm in length. Because the intrinsic Q-value of the MA core is low, acceleration without any tuning system also becomes possible. The first beam acceleration test using the HGC has been performed successfully at the HIMAC (Heavy Ion Medical Accelerator in Chiba). Furthermore, the dual harmonic RF and barrier bucket experiments have been carried out. Another advantage of the MA-loaded cavity is that it is easy to compensate the beam loading. The feed forward beam compensation was applied for both HGC on the test bench using an electron beam and MA-loaded cavity installed in the AGS for the barrier bucket experiment. A new development for high-Q HGC using a cut core configuration will be also reported.

Development of the KEK volume H− ion source

Characteristics and performance of the recently developed volume H− ion source at KEK are described in this article. In particular, observation of the H− beam intensity enhancement by introducing a very small amount of cesium vapor is shown in detail. The extracted H− beam current of 20 mA was obtained in the cesium-mode operation. The measured 90% normalized beam emittance was about 1π mm mrad for 12 mA beam, and emittance growth due to the space charge effect was observed when the beam intensity increased. We also made experiments on the cesium effect and found that the work function of the cesium-covered surface of the beam extracting plasma electrode might have an important role to enhance the H− beam intensity.

Preparation of Superconducting Y?Ba?Cu?O and Bi?Pb?Sr?Ca?Cu?O Compounds by Chelating Method

Superconducting Y?Ba?Cu?O (YBCO) and Bi?Pb?Sr?Ca?Cu?O (BPSCCO) compounds were prepared by a chelating method with various chelating agents, such as nitrilotriacetic acid (NTA), hydroxyethylethylenediaminetriacetic acid (HEDTA) and ethylenediaminetetraacetic acid (EDTA). Above 600?C, the precursors YBCO and BPSCCO turned into a mixture of metal oxides and BaCO3, which finally transformed into the almost single phase of YBCO at 850?930?C and into the high-Tc phase of BPSCCO at 840?C. The critical current densities of YBCO and BPSCCO in blocks of 1*4*15 mm3 were estimated to be as high as 350 and 500 A/cm2 at 77 K, respectively.

Copper Self-Sputtering by Planar Magnetron

Aiming at filling up deep holes with metal, self-sputtering of copper is performed in a wide pressure range of 10-2 Pa to 10-4 Pa. The high target current of 7 A to 10 A for a 4-inch planar magnetron target is essential to perform the self-sputtering process wherein a very high deposition rate of about 4 µm/min at 60 mm from the target surface is obtained. The lifetime of the planar target is from 1 h to 2 h. A new type of target which has protuberances on the erosion centers is produced by trial and error, and achieved a lifetime of 4 h. Deep holes on Si wafers, 1.17 µm in depth and 0.4 µm or 0.6 µm in diameter, are examined, and verry good bottom coverage of nearly 100% is obtained.

High‐intensity plasma‐sputter heavy negative‐ion source (invited)

A multicusp magnetic field plasma‐surface ion source, normally used for H−ion‐beam formation, has been modified for the generation of high‐intensity, pulsed, heavy‐negative‐ion beams suitable for a variety of uses. A brief description of the source and basic pulsed‐mode operational data (e.g., intensity versus cesium oven temperature, sputter probe voltage, and discharge pressure) are given. In addition, illustrative examples of intensity versus time and the mass distributions of ion beams extracted from a number of samples, along with emittance data, are also presented. Preliminary results obtained during dc operation of the source under low‐discharge‐power conditions suggest that sources of this type may alo be used to produce high‐intensity (mA) dc beams.

Acceleration of the polarized proton beam at the KEK 12 GeV ps

Abstract Acceleration of the polarized proton beam at the KEK PS up to 3.5 GeV is described. In the booster synchrotron, 75% of the linac beam polarization was preserved without any correction for the depolarizing resonances. In the main ring, almost 100% of the booster beam polarization was preserved at 3.5 GeV by the fast passage method for the intrinsic resonances and by the closed orbit correction for the imperfection resonances. The KEK PS is the first cascaded synchrotron which has demonstrated acceleration of a polarized beam.

Measurement of electron polarization of optically pumped sodium atoms

Abstract The electron-spin polarization of optically pumped sodium atoms for a polarized H− ion source was measured by a Faraday rotation method. This paper presents the theory of this scheme and some experimental results which have been obtained so far. When two pumping lasers were used, a sodium electron-spin polarization of about 90% was obtained at a target thickness of 1 × 1013n/cm2.